1) Field of the Invention
The present invention relates to a parking lot management system which provides information about a parking lot. The parking lot management system uses a wireless LAN (Local Area Network) system.
2) Description of the Related Art
A service is known which offers information about availability of parking spaces. The service uses a server to manage information and an on-vehicle communication apparatus connected to the server via the Internet. Japanese Patent Kokai No. 2002-109693 discloses a system which has a function to distribute real time information about availability of parking lots near an area designated by a user. The system uses an unattended parking lot management facility equipped with an availability information notification function, and a server to manage availability information supplied from the unattended parking lot management facility. Accordingly, the system distributes the information to the on-vehicle communication apparatus having capability to access to the Internet. The unattended parking lot management facility is provided with, for example, a vehicle information management device which detects the number of vehicles parked in each parking lot by an associated sensor. If the parking lot has an available space, the vehicle information management device transmits the information to an availability information management server via the Internet.
Another type of information providing system is disclosed in Japanese Patent Kokai No. 2002-318959, which includes a center server and a communication terminal installed at a store. The communication terminal is connected to the center server via a communication network. The center server stores availability information supplied from the communication terminal at the store, and then transmits the availability information to a user's communication terminal having capability to access to the Internet. This system may be used to provide the information about the availability of a parking space. For instance, the system can provide information about an availability of a parking lot near the designated railway station and the number of available spaces in the parking lot.
There is provided a service such that the general public can wirelessly connect to the Internet by means of a notebook computer or a personal digital assistants (PDA). The service is established by a wireless LAN system which has an installed base station for transmitting and receiving data by wireless communication. Such wireless LAN system complies with communication standards. Among them, the IEEE (Institute of Electrical and Electronics Engineers) 802.11b is generally applied. Alternatively, the IEEE 802.11a , the Bluetooth or the like may be applied.
As an example of such service using the wireless LAN system, there is a “hotspot” service which has a wireless network installed at areas where many people gather such as coffee shops, restaurants, hotels, convenience stores, airports and railway stations, so that these people can use the Internet. It should be noted that the term “hotspot” is a registered trademark of the NTT Communications Corporation, Tokyo, Japan (Japanese Registered Trademark No. 4539387), even though it is used to express the above-described service. This “hotspot” service is achieved in such a manner that a large company, e.g., the NTT Communications Corporation, installs a system at a store or the like who ties up with the company, and then the store owner himself or a railway company installs a commercially available wireless LAN system at the store, train or station so that customers can use the system.
When the scale of the store or the number of customers is large, a large parking space is required for a parking lot. In some cases, a plurality of floors are required for such parking lot. A customer who will use such parking lot may be able to recognize whether the parking space is available or not before entering the parking lot. However, once the customer enters the parking lot, it is often difficult for the customer to smoothly park the vehicle, because the parking lot may be too large to find out the available space.
The systems disclosed in Japanese Patent Kokai No. 2002-109693 and Japanese Patent Kokai No. 2002-318959 can detect a parking lot having an available space and can provide a customer with information about such parking lot. However, these systems can not provide a customer with information to help the customer easily find a vacant space in the parking lot.
Furthermore, these systems are based on the assumption that a telephone line mainly accessed by a mobile phone is used to connect to the Internet. A communication speed of such application is thus too slow for the moving vehicle to obtain the parking lot information. Moreover, the moving vehicle sometimes can not receive a radio wave properly.
When the wireless LAN system such as the ‘hotspot’ is applied to the systems disclosed in Japanese Patent Kokai No. 2002-109693 or Japanese Patent Kokai No. 2002-318959, countless number of base stations are required, and therefore the wireless LAN system can not be used. This is because the system is not used in a limited area such as a railway station or a store, but the system is used in an unlimited area such as a road around the railway station.